数据结构学习（四） Java链表实现

package linklist;

/**
 * @Title: LinkedListDemo
 * @ProjectName demo
 */
public class LinkedListDemo<E> {

    private class Node {
        private E e;
        private Node next;

        public Node(E e, Node next) {
            this.e = e;
            this.next = next;
        }
        public Node(E e) {
            this(e, null);
        }

        public Node() {
            this(null, null);
        }

        @Override
        public String toString() {
            return e.toString();
        }
    }

    private int size;
    private Node dummyHead;

    public LinkedListDemo() {
        size = 0;
        dummyHead = new Node();
    }

    public int getSize() {
        return this.size;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public void add(int index, E e) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("add error index.");
        }
        Node prev = dummyHead;
        for (int i = 0; i < index; i++) {
            prev = prev.next;
        }
        prev.next = new Node(e, prev.next);
        size ++;
    }

    public void addFirst(E e) {
        add(0, e);
    }

    public void addLast(E e) {
        add(size, e);
    }

    public E remove(int index) {
        if (index < 0 || index >= size) {
            throw new IllegalArgumentException("remove error index.");
        }
        Node prev = dummyHead;
        for (int i = 0; i < index; i++) {
            prev = prev.next;
        }
        Node curNode = prev.next;
        prev.next = curNode.next;
        curNode.next = null;
        return curNode.e;
    }

    public E removeFirst() {
        return remove(0);
    }

    public E removeLast() {
        return remove(size - 1);
    }
    public void removeElement(E e){
        Node prev = dummyHead;
        while (prev.next != null) {
            if (prev.next.e.equals(e)) {
                break;
            }
            prev = prev.next;
        }
        if (prev.next != null) {
            Node delNode = prev.next;
            prev.next = delNode.next;
            delNode.next = null;
            size --;
        }
    }

    public void set(int index, E e) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("set error index");
        }
        Node cur = dummyHead.next;
        for (int i = 0; i < index; i++) {
            cur = cur.next;
        }
        cur.e = e;
    }

    public E get(int index) {
        if (index < 0 || index >= size) {
            throw new IllegalArgumentException("Get error index");
        }
        Node cur = dummyHead.next;
        for (int i = 0; i < index; i++) {
            cur = cur.next;
        }
        return cur.e;
    }

    public E getFirst() {
        return get(0);
    }

    public E getLast() {
        return get(size - 1);
    }
        
    
    public boolean contains(E e) {
        Node cur = dummyHead.next;
        while (cur != null) {
            if (cur.e.equals(e)) {
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        for (Node cur = dummyHead.next; cur != null; cur = cur.next) {
            sb.append(cur.toString() + "--->");
        }
        sb.append("NULL");
        return sb.toString();
    }
}